Underreamer



E. R. BECKERT.

UNDERREAMER.

I AT 0N ILED DEC 20| i913.

Patented May 11; 1915.

2 SHEiTS--SHEET 2.

UNTTED STATES PATENT onirica.

EMIL F 3ECKERT, 0F CHIcaGo, ILLINoIs. UNDERBEaMnn.

Specication of Letters Patent.

'y Patented May 11, 191.5.

Application -led llecember 20, 1913. Serial No. 808,017.

Improvements in Underreamers, of which the following is a specliication.

My invention re atesin generalto tools for drilling wells, such as oil,gas, and Artesian, and more particularly to underreamers. In drillingwells -it is necessary that the hole should be enlarged in advance ofthe pipe or casingto a diameter slightly greater than that of the usualshoe at the end of the casing and that of the couplings which connectthe successive sections of the casing, 1n order that Vthe .casing may bereadily driven downwardly as the work of drilling pro' 4esses. n isaccomplished by a tool `own as an underreamer, which must be socontracted that it may pass freely downwardly .and upwardly through thecasing, and when fbelow the lower end of the casing will kexpand so asto drill the 'hole to la diam- .eter of the requisite size relatively tothat of 4 the casin The .obJects of my invention are to provide anunderreamer in which the cutting bits will be so securely supported onthe-mandrel as to avoid all danger of their accidental detachment; inwhich the bits when in operative osition will directly abut againstsubstantlal portions of the mandrel so 'as to be vcapable ofwithstanding the great strains,

incident to theblows delivered in drilling; in which the bits willautomatically yield inwardly should they encounter 'heavy cavings fromthe sides -of the hole above the bits in -action,`and which would makeit 'impossible to withdraw the bits in expanded position without thisautomatic feature; and in which the bits will be automatically foldedinto a compact position and drawn within the casing by a direct upwardpull without necessitating a preliminary movement to unlock the bitsfrom the mandrel. f A further object of my invention is to provide anlunderreamer, which will be simple and strong in construction, eiiicientin operatiomand durable in use.

Aend of the tangular block D, of a cross Y .with a sllding fit withinthe chamber, such lMy invention will be more fully described hereinafterwith reference tov the accompanying drawings, in which the same isillustrated as embodied in a convenient and practical form, and inwhich- Figure 1 is a vertical section, the bits being shown in theiroperative position; Fig. 2 is a view similar to Fig. 1 showing the bitsin folded position within the surrounding casing; Fig. 3 is aperspective view ofthe pair of bits removed from the mandrel; Fig. 4 isa side elevational view of the lower end of the mandrel, the `bitshaving been .res moved therefrom; Fig. 5 is an' elevational view of thelower end o'f the mandrel with the bits in position; Fig. 6 is a planview looking upwardly with respect to Fig. ',5; and Fig. 7 is aperspective view of the bits separated and placed side by side,

Similar characters are used to designate similar parts of the severalfigures of the p drawings.

Reference letter A indicates a pipe such as is driven into the ground asthe work of drilling a wel-l progresses, and which serves as the casingthrough which the oil, gas, or water flows upwardly to the surface of'the ground.

B designates a shoe secured to the lower pipe A, the lower end of suchshoe being beveled outwardly, as shown at b. i

C designates a mandrel, which may 'be provlded at its upper end with anysuitable means for raising and lowering the -same,

such means not being shown, as they form no part of my invention but areold and well-known in the art. The mandrel is provided with a chamber cin its lower end,

which is preferably rectangular in cross section. Located withinthechamber c is a recsection to move block being provided on its lowersurface with downwardly diverging cam surfaces D and D2. Secured to thelblock D, and pro jecting upwardly therefrom, is a rod d which extendswithin an opening d in the portion of the mandrel above the chamber c. Aspring E surrounds the rod d and bearsat its lower end upon the block Dand at its `upper end against a shoulder e formed in the mandrel aroundthe lower end of the opening d therein.

F and F2 designate apair o f bits which interlock with each other andare mounted to oscillate within the lower end of the mandrel C. Atubular bushing F extends through alined openings in the overlappedportions of the bits and serves s a pivot upon which the bits may beoscil ated. Extending through the tubular bushing F is a rod f which issupported at itsends by the depending side portions C', C2 of themandrel. The bits are provided withv upwardly projecting shanks f andf2, respectively, which are-curved at their upper ends and fit withinthedownwardly idiverging* cam surfaces D and D2 of the' block D. The bitsare provided with` concentric curved shoulders G and G2, respectively,above their axes, and such surfaces coperate withoverlyingcorrespondingly curved shoulders g and g2 formed in the mandrelat each side of the lower end of the chamber c therein. The bits arealso provided with shoulders H and H2, respectivel lying in a lanetransverse of theaxes o the bits and adapted to engage -shoulders h andh2, respectively, formed at opposite sides of the lower end of thechamber c of the mandrel and located intermediate of the curvedshoulders g and g2. The bits are also provided with concentric curvedshoulders K and K2, respectively, located below the horizontal plane oftheir axes and adapted to coperate with correspondingly curvedconcentric shoulders 7c and`k2, the shoulder c being located on the bitF2 in position to coperate with the shoulder K on 4the bit F', and theshoulder K2 on the bit F2 being adapted to coperate with the shoulder k2on the bit F. In orderl that the bits may so engage each other as toprevent any relative axial movement, they are provided with lugs L andL2 extending in planes transverse to the axes of the bits, which, whenthe bits are ininterlocked engagement as shown in Figs. 3 and 5, overlapeach other,

the lug L being received within a recess l in the bit F2 intermediate ofthe shoulder K2 and the lug L2 thereon, and the lug L2 being received ina recess Z2`between the shoulder K and lug L of the bit F.

By reference to Fig. 2 it will be seen that when the bits are oscillatedto their contracted position to move within the pipe A, the cuttingedges m and m2 are prevented from engaging the inner surface of thepipe, by reason offthe overlying projections M and M2. which bearagainst the inner surface of the pipe. When, however, the bits areoscillated-'to their operative position below the end of the pipe, asshown in Fig. 1,

`the cutting edges and'overlying projections are located in verticalrelation so that the cutting edges may engage the material to be cut.

The manner of using and operation of my improved underreamer is asfollows: In order to insert the underreamer in the pipe A, the lowerends of the bits are pressed toward each other until their combinedcross section is slightly less than the diameter of the pipe. The inwardoscillation of the lower ends of the bits causes the upper ends of theirshanks f and f2 to separate, thereby compressing the spring E throughthe upward movement imparted to the block D by reason of'the engagementof the ends of the' Shanks with the inclined diverging cam surfaces Dand D2. The underreamer may then be inserted in the pipe A and the partsoccupy the relative positions shown in Fig. 2. When the underreamer isprojected downwardly below the. shoe B on the lower end of the pipe A,the bits F', F2 are no longer retained in their contracted position bythe pipe, and hence are automatically oscillated outwardly by reason ofthe expansion of the spring E forcing downwardly the block D, which,through the inclined cam surfaces D and D2 thereon, forces the upperends of the Shanks of the bits to gether, as shown in Fig. 1.' Thecutting edges of the bits are consequently oscillated outwardly so as todrill a hole of a diameter slightly greater than tliat of the shoe atthe lower end of the pipe. When the bits are subjected to the stra-insincident to impact of the earth, such strains are transmitted to themandrel through the engagement of the shoulders H and H2 with theshoulders It and h2 on the mandrel, and also through the engagement ofthe concentrically curved shoulders G and G2 on the bits with thecorrespondingly curved shoulders g 'andg2 in the mandrel; The strains towhich the individual bits are subjected are distributed toA both bits byreason of the coperating concentric pairs of shoulders K and k and K2and k2, so that each bit serves to strengthen the other and to increaseits capacity to resist drilling strains. When it is desired to lift theunderreamer upwardly through the pipe A, it is merely necessary to exerta direct upward pull, which, through the engagement of the projectingsurfaces M and M2 on the bits with the lower outwardly Haring' end b ofthe shoe B, oscillates the bits to the contracted position necessary forthem to pass into the pipe A, as shown in Fig. 2.

From the foregoing description it will be observed that in -my lmprovedunderreamer the bits are connected to the mandrel at their strongestportions, so that all danger of the bits becoming detached from themandrel, by reason of the breaking of the engaged parts, is avoided. Itwill further be observed that in my improved underreamer when the bitsare in operative position the strains to which they are subjected aredirectly communicated to the mandrel through the coperating shoulders onthe bits and on the mandrel, and that the strains. to which theindividual bits are subjected are distributed to both bits byvreasoirr-of. the cooperating shoulders on the bits. It will be furtherevident that in my improved underreamer the cutting edges when in oerative positions project radially farther t an any of the overlyingparts of the underreamer,

and hence there is no danger of any of the parts ofthe underreamerbecoming, broken through contact with the materials Worked upon, andthat even when the bits are worn away through usage and throughresharpen ing the cutting edges will still project radially beyond theoverlying portions of the underreamer and thereby protect them frominjury. It will also be seen that should the bits become wedged When inexpanded position by cavings .from above, they would collapse beforebreakage would occur on heavy upward pulls, inasmuch as the spring Ewould be compressed and allow the bits to oscillate inwardly, shouldthey be subjected to excessive strains.

While I have described my invention with more or less minuteness and asbeing embodied in certain precise forms, yet it will be understood thatIdo not desire to limit myself thereto unduly, or any more than ispointed out in the claims. On the contrary, I contemplate.. all properchanges in form, construction, and arrangement, the 4omission ofimmaterial parts, and the substitution of equivalents, as circumstancesmay suggest or necessity render expedient.

1. In an underreamer, the combination with a mandrel having a chamber inthe lower portion thereof, of a pair of complemental overlapping bitsextending Within the chamber in the mandrel, a pivot rod passing throughthe overlapped portions of said bits and supported at its ends by themandrel, concentric coperating shoulders on the overlapped portions ofsaid bits for transmitting the strains on each bit to the other bit, andmeans for oscillating said bits to project their cutting edges beyondthe vertical plane of the mandrel. r

2. In an underreamer, the combination with a mandrel having a chamberinthe lower portion thereof, of a pair of complemental overlappingbitsvextending within the chamber 'in-the mandrel, a tubular bushlngpassing through v'the overlapped por-r tions of said bits, a kpivot -rodthrough said bushing and supported atnts ends by the mandrel, means oroscillating said bits to project their cutting edges beyond the verticalplane of the mandrel, and coperating shoulders on the mandrel andbitsarranged to contact with each other when the bits are oscillated tooutwardly project their cutting edges.

3. In an linden-samer, the combination with' a mandrel having a. chamberin the lower portion thereof, of a pair of complemental overlapping bitsextending within the ychamber in the mandrel, a 'pivot rod passingthrough the overlapped portions of said bits and supported at its endsby the mandrel, meansl for oscillating said bits to project theircutting edges beyond the ver-v tical plane of the mandrel, concentriccooperating shoulders on the overlapped portions' of said bits fortransmitting the strains on each bit to the other bit, and cooperatingshoulders on the mandrel and bits arranged to contact with each otherv'when the bits are oscillated to outwardly project their cutting edges.

4c. In an undei'rcamer, the combinationwith a mandrel having a chamberinthe lower portion thereof, of a -pair of comple'- mental overlappingbits extending within the chamber in the mandrel, each'of lsaid bitshaving an upwardly projecting shank mandrel of less Width inthe-directionof ysus extending into a central chamber in -the.V i

the axis of the bits than the chamber in which the bits extend, a pivotrod passing through the overlapped portions of said bits and supportedat its'ends by the mandrel,

means for oscillating said bits to project shoulders on the bits totransmit strains from the bits to the mandrel.

5. In an underreamer, the combination with a mandrel having a chamberwithin the lower part' thereof, of a pair of bits pivotally supported atthe lower end of said v mandrel, means for automatically oscillate ingsaid bits to project their cutting edges outwardly, a curved shoulder oneach bit concentric to. and above the 'axis thereof, shoulders on saidmandrel cooperating with said shoulders on the bits to transmit strainsfrom the bits to the mandrels, a' lateral shoulder on` each'bit at onevside of its axis, shoulders on said mandrel with whichy the lateralshoulders on the bits engag'exazhen the bits are oscillated to projecttheir cutting edges4 outwardly, and coperating shoulders o n said bitsto transmit strains from one bit to the other.

6. In an underreamer, the combination with a mandrel, of a pair ofoverlapping bits pivotally supported on said mandrel and having a commonaxis of oscillation, means for automatically oscillating said bits toproject their cutting edges beyond the vertical plane of the mandrel,and interlocking lugs projecting radially from the axis of the bits andrecesses on said bits to prevent relative lateral movement thereof orindivdual loss of a bit should breakage occur 15 from abusive use.

In testimony whereof, I have subscribed Copies of this patent may beobtained for ve cents each, by addressing the Commissioner of Patents,Washington, Dl C.

